The present invention relates to a method and a device for removing sections of defined length from a continuously manufactured extruded panel composed of a rigid foam core disposed between two outer layers.
In the known methods for removing sections from a continuously produced panel, a sawing device is brought with its saw blade into cutting position and displaced at the feed rate of the extruded panel parallel to the latter and simultaneously transversely for removal of a section. After the cut, the saw blade is turned and moved back, then brought once more into cutting position and displaced at the feed rate of the extruded composition parallel to the latter and simultaneously transversely in the opposite direction for removal of the next section, and so on (DE 35 00 751 C2).
Extruded panels and/or panel sections with a rigid foam core generally have sheet-metal outer layers or less rigid outer layers such as, for example, roofing felt, cardboard, or paper. Particularly in the case of metal outer layers, the edges often extend beyond the rigid foam core and are profiled so that the individual sections may be assembled to form, for example, walls or roofs.
Apart from the nature of the outer layers and the thickness of the rigid foam core, sections are required in various lengths and widths and this makes cost-effective production difficult. Manufacture of the extruded panel is carried out on a xe2x80x9cso-calledxe2x80x9d twin-belt conveyor, which has a sawing device disposed downstream thereof.
The cutting speed depends upon the nature of the outer layers and is adjustable without taking up too much time. Tearing of the outer layers by the saw blade, which may occur as a result of selecting the incorrect (usually too high) cutting speed, should be avoided. The cut is therefore usually started at a lower speed and then increased. Towards the end of the cut, the cutting speed is reduced again. During the cutting process, the extruded panel is being continuously manufactured in the usual manner at a constant feed rate without interruption. In the course of each feed travel, which corresponds to the length of a section portion to be removed, both the cutting operation and the return travel of the saw have to be completed.
The twin-belt conveyor should be adjusted to the width of the extruded panel to be produced in each case. In the case of the sawing device, which is designed for the maximum extruded panel width, a great deal of time is wasted in transverse travel before and beyond the actual cut. Such wasted time adds up to the time available to the sawing device for the return travel. As a result, the removal of panel sections below a specific minimum length has been considered to be impossible.
The entire transverse travel path of the sawing device could, of course, be adapted to the respective extruded panel width. It would then be possible to remove extruded panel sections of smaller length but the necessary modification time is considerable and therefore prohibitive. Modification for small production runs is also uneconomical.
It is an object of the present invention to provide a device and a method for removing sections of defined length from a continuously produced extruded panel, which saves some of the transverse travel time of the cutting device and does not require the considerable modification times required in the known processes, thereby making it possible to remove extruded sections of very small length, and indeed also within a smaller production run, in a profitable manner.
These and other objects which will be apparent to those skilled in the art are achieved by the present invention in which an adjustable program controller fixes optimum start-of-cut positions relative to a reference point and immediately in front of the edges of the extruded panel for each section to be removed. The cutting device is immediately moved back after the cut section has been removed and, in the process, the cutting blade is positioned (e.g., by turning) for making the next cut. The cutting device is brought into the next optimum start-of-cut position during the return travel.